Problem: Solve for $x$ : $9\sqrt{x} + 8 = 6\sqrt{x} + 4$
Solution: Subtract $6\sqrt{x}$ from both sides: $(9\sqrt{x} + 8) - 6\sqrt{x} = (6\sqrt{x} + 4) - 6\sqrt{x}$ $3\sqrt{x} + 8 = 4$ Subtract $8$ from both sides: $(3\sqrt{x} + 8) - 8 = 4 - 8$ $3\sqrt{x} = -4$ Divide both sides by $3$ $\frac{3\sqrt{x}}{3} = \frac{-4}{3}$ Simplify. $\sqrt{x} = -\dfrac{4}{3}$ The principal root of a number cannot be negative. So, there is no solution.